Blood flow restriction devices in the form of inflatable cuffs are known from the prior art, e.g., from U.S. Pat. No. 4,637,394 B, which cuffs can be placed on a limb and be inflated in order to create blood flow restriction in the limb. To create blood flow restriction in the limb, the inflatable cuff is connected to a compressed gas source and inflated with compressed gas (for example, compressed air) to such an extent that the cuff exerts a sufficiently high pressure on the limb so as to interrupt, at least to a large extent or completely, the flow of blood through the part of the limb that is enclosed by the cuff. Such blood flow restriction devices are used, for example, in surgical interventions on limbs, in which extensive or complete blood flow restriction or even a bloodless field in the area of operation must be created and maintained during surgery in order to make the surgical procedure easier or to reduce the risk of injury to the vascular system. To inflate the cuff, the cuff is connected to a variable compressed gas source via a hose, by means of which the cuff can be inflated with a variable predefined pressure. The compressed gas source is controlled by a control device, by means of which an operator can control the inflation of the cuff as well as the release of pressure when the blood flow restriction is to be stopped.
Because of the extremely variable and individual sizes and shapes of the limbs of patients, a hospital, as a rule, must keep in stock a multiplicity of tourniquet cuffs in different sizes and shapes. This is labor-intensive and expensive. To solve this problem, U.S. 2013/028 96 12 A1 proposes an inexpensive tourniquet cuff for one-time use, which can be used on different non-cylindrical limbs. This tourniquet cuff comprises a substantially arcuate outer wrap which contains an inflatable bag. Disposed on the outside surface of the wrap is a fastening belt made of an unstretchable material. Using this fastening belt, the cuff, the end sections of which are looped about the limb so as to overlap, is attached to the limb. The wrap is made of a textile material, in particular a knitted or woven nylon fabric, which is sterilized before the cuff is attached to a limb. Because of the flexible textile structure of the wrap of the cuff, there is the risk of creases forming in the wrap. Creases can form especially while the cuff is being inflated since the inside circumference becomes shorter than the outside circumference, thereby creating excess material which leads to the formation of creases. In addition, the prior-art tourniquet cuff disclosed in U.S. 2013/028 96 12 A1 cannot be adequately cleaned and sterilized and is intended for one-time use only, which, with respect to the generation of waste and from the standpoint of resource efficiency, is a considerable drawback.
Furthermore, it has also been demonstrated that when using the prior-art tourniquet cuffs which comprise a wrap made of a textile fabric or rubber and which are looped about the limb so as to at least partially overlap, the pressure exerted by the cuff on the underlying limb is not distributed uniformly. This non-uniform pressure distribution is attributable, on the one hand, to the irregular shape of the limb, which, as a rule, does not have a uniformly cylindrical shape and, on the other hand, to the creases that form in the textile fabric or in the rubber material during placement and inflation of the cuff. To ensure that the pressure exerted on the limb is as uniform as possible, the cuff must be wrapped around the limb so as to be absolutely flat and creaseless. Creases and overlaps produce pressure points which can later manifest themselves as tension blisters or skin necroses.
A surgical cuff for attachment to a limb is known from U.S. Pat. No. 2,291,785 B. This cuff comprises a truncated cone-like and tubular main body which has an inside and an outside wall made of a thin, flexible and stretchable material, with the two walls being connected to each other along their outside ends and with the remaining wall area extending at a distance from each other. On one end, the two walls are connected to each other, thereby forming an external annular portion which is flexible and stretchable both in the longitudinal and in the transverse direction. Disposed between the two walls are a plurality of layers made of a woven fabric, which layers are connected to each other and to the two walls by means of a rubber adhesive. On the other end that lies opposite to the external annular portion, the walls are reinforced with textile strips, so that the main body, although flexible and bendable as a whole, is stretchable only in the area of the annular portion. Located opposite to the inside wall and radially disposed on its inside surface is a lining wall made of a flexible and stretchable rubber material, the edge portions of which lining wall are connected to the two walls so that a sealed annular chamber is formed between the inside wall of the main body and the lining wall, which chamber can be inflated by means of compressed air. When unpressurized and uninflated, the lining wall and the oppositely lying inside wall extend coaxially relative to each other. Because of the stiffness of the main body, essentially only the lining wall expands radially inwardly when compressed air is blown into the chamber. Along four diametrically oppositely lying areas, the lining wall is attached in the longitudinal direction to the inside wall, thereby causing indentations to be formed in these areas, which have a higher resistance to the stretching of the lining wall, with the result that during inflation, between these indentations, radially inwardly projecting bulges form which extend in the longitudinal direction. The uninflated (unpressurized) main body is placed on a limb and is subsequently inflated, during the course of which the radially inwardly swelling bulges exert pressure on the limb. The advantage of this design is that pressure is not exerted over the entire circumferential area of the main body, but only on the area of the bulges, so that this pressure allows the flow of arterial blood in the limb but largely interrupts the flow of venous blood. However, tourniquet cuffs require that the pressure exerted on the limb be uniform across the entire circumference so as to arrest the flow of blood and to create blood flow restriction.
As the foregoing shows, there is a need for an improved tourniquet cuff for placement on a limb, which cuff can be thoroughly and easily cleaned and sterilized, easily and quickly applied to the limb and able reliably to create a long-lasting blood flow restriction in the limb, while at the same time ensuring that the pressure exerted by the tourniquet cuff on the limb is distributed as uniformly as possible and that stresses on the tissue and the skin of the limb are minimized as much as possible.